[Release-3.13] Fix a bug that was causing compute node self‑termination to hang on Ubuntu 24.04 nodes

[hehe7318]

Description of changes

• Detect OS before run the self-termination command
• If the OS is ubuntu2404, run systemctl poweroff --force instead of shutdown -h now
• Added test cases to cover the changes

Tests

• I created a AL2 and Ubuntu2404 cluster to manually test. Test done. Works as expected.

Checklist

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